Abschätzung der Belastung des Menschen durch bodenbürtige Stoffe

Different concepts for hazard assessment of 2,3,7,8-TCDD in soil are presented and a comparison of the approaches is made. Both approaches clearly show that hazard assessment should be site and use specific.     

In vitro studies of the submerged angiospermRuppia maritima: Auxin and cytokinin effects on plant growth and development

Axenic tissue cultures ofRuppia maritima L. were established and propagated clonally in vitro from terminal rhizome segments collected from Tampa Bay, Florida, USA. Cultures were maintained in a base medium consisting of synthetic seawater supplemented with half-strength Murashige and Skoog salts and 1% sucrose at pH 5.6. The effects of five cytokins [6-furfurylaminopurine (kinetin), 6-benzylaminopurine (BAP), 2-isopentyladenine (2iP), 6-(4-hydroxy-3-methyl-but-2-enylamino) purine (zeatin), andn-phenyl-n-1,2,3-thidiazol-5yl urea (thidiazuron)] and one auxin [napthalene acetic acid (NAA)] on explant growth and development were investigated. Cytokinin additions resulted in a 3- to 4-fold increase in nodal production, branching, and biomass ofR. maritima after 12 wk in culture. Cultures responded in a dose-dependent manner to 2iP but exhibited broad dose-response curves to kinetin, BAP, zeatin, and thidiazuron. NAA addition resulted in increased leaf and internodal lengths, but reduced the number of leaves per node and the rhizome biomass. The addition of NAA almost completely suppressed root growth in media without cytokinins and had an antagonistic effect on nodal production and branching in cytokinin-supplemented media.     

Interlaboratory evaluation of endotoxin analyses in agricultural dusts--comparison of LAL assay and mass spectrometry

Endotoxin exposure is associated with wheeze and asthma morbidity, while early life exposure may reduce risk of allergy and asthma. Unfortunately, it is difficult to compare endotoxin results from different laboratories and environments. We undertook this study to determine if lipopolysaccharide (LPS) extraction efficiency could account for differences among laboratories. We generated and collected aerosols from chicken and swine barns, and corn processing. We randomly allocated side-by-side filter samples to five laboratories for Limulus assay of endotoxin. Lyophilized aliquots of filter extracts were analyzed for 3-hydroxy fatty acids (3-OHFAs) as a marker of LPS using gas chromatography-mass spectrometry. There were significant differences in endotoxin assay and GC-MS (LPS) results between laboratories for all dust types (p < 0.01). Patterns of differences between labs varied by dust type. Relationships between assay and GC/MS results also depended on dust type. The percentages of individual 3-OHFA chain lengths varied across labs (p < 0.0001) suggesting that each lab recovered a different fraction of the LPS available. The presence of large amounts of particle associated LPS and absence of a freezing thawing cycle were associated with lower correlations between LPS and bioactivity, consistent with an absence of Limulus response to cell-bound endotoxin. These data suggest that extraction methods affect endotoxin measurements. The LAL methods may be most suitable when comparing exposures within similar environments; GC-MS offers additional information helpful in optimizing sample treatment and extraction. GC-MS may be of use when comparing across heterogeneous environments and should be considered for inclusion in future studies of human health outcomes.     

Plant and Soil System Responses to Ozone After 3 Years in a Lysimeter Study with Juvenile Beech (Fagus sylvatica L.)

A lysimeter study was performed to monitor effects of elevated ozone on juvenile trees of Fagus sylvatica L. as well as on the plant–soil system. During a fumigation period over almost three growing seasons, parameters related to plant growth, phenological development and physiology as well as soil functions were studied. The data analyses identified elevated ozone to delay leaf phenology at early and to accelerate it at late developmental stages, to reduce growth, some leaf nutrients (Ca, K) as well as some soluble phenolics (hydroxycinnamic acid derivatives, total flavonol glycosides). No or very weak ozone effects were found in mobile carbon pools of leaves (starch, sucrose), and other phenolic compounds (flavans). Altered gene expression related to stress and carbon cycling corresponded well with findings from leaf phenology and chemical composition analyses indicating earlier senescence and oxidative stress in leaves under elevated ozone. Conversely in the soil system, no effects of ozone were detected on soil enzyme activities, rates of litter degradation and lysimeter water balances. Despite the fact that the three reported years 2003–2005 were climatically very contrasting including a hot and dry as well as an extremely wet summer, and also mild as well as cold winters, the influence of ozone on a number of plant parameters is remarkably consistent, further underlining the phytotoxic potential of elevated tropospheric ozone levels.     

Aufnahme von Cyanid in Pflanzen

Zusammenfassung  Cyanide entstehen bei der Pyrolyse von Kohle, und bei der Gasreinigung wird Blaus?ure als Berliner Blau gef?llt. Diese Abf?lle sind heute h?ufig Bestandteil von innerst?dtischen Altlasten. Cyanwasserstoff HCN (Blaus?ure) ist ein schnell wirksames und starkes Gift; eisenkomplexierte Cyanide im Boden sind jedoch weit weniger giftig. Die Phytotoxizit?t von freiem Cyanid wurde für Korbweiden (Sálix viminális) mit dem Baum-Transpirationstest bestimmt. Der EC₁₀ liegt für t=72 h bei 0,76 mg KCN (0,3 mg CN) je Liter, der EC₅₀ bei 4,47 mg/l KCN. Langfristig sind 5 mg/l KCN t?dlich. Balsampappeln (Pópulus trichocárpa) k?nnen in bis zu 2500 mg/l Ferroferricyanid (Berliner Blau) überleben, wenn auch mit Wachstumsst?rungen. Weiden überlebten in einem Gaswerksboden mit bis zu 452 mg/kg Gesamt-CN. Aus der N?hrl?sung wurde mehr freies CN aufgenommen als aus dem Boden. M?glicherweise wird auch komplexiertes Cyanid in die Bl?tter verlagert. In Erlenmeyern mit Pflanzen wurde freies Cyanid bei sublethaler Dosis rasch aus der N?hrl?sung eliminiert. Die Bepflanzung mit geeigneter Vegetation k?nnte eine L?sung für viele cyanid-kontaminierte Gaswerks- und Minengel?nde sein. OnlineFirst: 09. 01. 2001     

Ultrafine particles at workplaces of a primary aluminium smelter

The number concentration and size distribution of ultrafine particles in a S?derberg and a prebake potroom of an aluminium primary smelter have been measured using a scanning mobility particle spectrometer. The particle morphology was studied by transmission electron microscopy (TEM). The study shows the existence of elevated number concentrations of ultrafine particles in both potrooms. The main source of these particles is likely to be the process of anode changing. The ultrafine particles were measured directly at the source but could also be identified as episodes of high number concentrations in the general background air. Unlike the larger particles belonging to the 50-100 nm mode, the nanoparticle mode could not be detected in the TEM indicating that they may not be stable under the applied sampling conditions and/or the high vacuum in the instrument.     

Hydrodynamics,diffusion-boundary layers and photosynthesis of the seagrasses Thalassia testudinum and Cymodocea nodosa

Photosynthetic rates of aquatic plants frequently increase with increasing current velocities. This is presumably due to a reduction in the thickness of the diffusion boundary-layer which allows for a higher carbon availability on the plant surface. Blades of the seagrasses Thalassia testudinum and Cymodocea nodosa exposed to different current velocities under controlled laboratory conditions, showed increased photosynthetic rates with increasing flow only at low current velocities (expressed as blade friction velocities, u _*). Carbon saturation of photosynthetic processes occurred at a relatively low u _* level (0.25 cm s^-1) for T. testudinum collected from a calm environment compared to C. nodosa (0.64 cm s^-1) collected from a surf zone. No further enhancement of photosynthetic rates was observed at higher u _* levels, suggesting limitations in carbon diffusion through the boundary layer below critical u ^* levels and possible limitations in carbon fixation by the enzymatic system at higher u _* levels. These results, as well as those of previous theoretical studies, assumed the flow on the immediate seagrass-blade surface to be hydrodynamically smooth. The presence of epiphytes and attached debris causes the surface of in situ seagrass blades to be exposed to flows ranging from smooth to rough-turbulent. As a consequence, the boundary-layer thickness on moderately epiphytized blades under medium to high flow-conditions is not continuous, but fluctuates in time and space, enhancing carbon transport. In situ u _* levels measured directly on blades of seagrasses indicate that T. testudinum and C. nodosa can be exposed to conditions under which the boundary layer limits photosynthesis during short periods of time (milliseconds) during low-energy events. As waves cause the thickness of the diffusion boundary-layer to fluctuate constantly, carbon-limiting conditions do not persist for prolonged periods.     

Vivianite precipitation and phosphate sorption following iron reduction in anoxic soils

Phosphorus retention in lowland soils depends on redox conditions. The aim of this study was to evaluate how the Fe(III) reduction degree affects phosphate adsorption and precipitation. Two similarly P-saturated, ferric Fe-rich lowland soils, a sandy and a peat soil, were incubated under anaerobic conditions. M?ssbauer spectroscopy demonstrated that Fe(III) in the sandy soil was present as goethite and phyllosilicates, whereas Fe(III) in the peat soil was mainly present as polynuclear, Fe-humic complexes. Following anoxic incubation, extensive formation of Fe(II) in the solids occurred. After 100 d, the Fe(II) production reached its maximum and 34% of the citrate-bicarbonate-dithionite extractable Fe (Fe(CBD)) was reduced to Fe(II) in the sandy soil. The peat soil showed a much faster reduction of Fe(III) and the maximum reduction of 89% of Fe(CBD) was reached after 200 d. Neoformation of a metavivianite/vivianite phase under anoxic conditions was identified by X-ray diffraction in the peat. The sandy soil exhibited small changes in the point of zero net sorption (EPC?) and P(i) desorption with increasing Fe(III) reduction, whereas in the peat soil P desorption increased from 80 to 3100 μmol kg?1 and EPC? increased from 1.7 to 83 μM, after 322 d of anoxic incubation. The fast Fe(III) reduction made the peat soils particularly vulnerable to changes in redox conditions. However, the precipitation of vivianite/metavivianite minerals may control soluble P(i) concentrations to between 2 and 3 μM in the long term if the soil is not disturbed.